Pump.



No. 629,750. Patented July 25, |899.

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PUMP.

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Patented July 25, |899. H. S. MAXIM.

PUMP.

Appliention filed Nov, 28, 1898.

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{Application filed Nov. 28, )898,i (No Model.)

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UNITED STATES PATENT EEicE.

IIIRAM STEVENS MAXIM, OF LONDON, ENGLAND.

PUMP.

SPECIFICATION forming part of Letters, Patent N o. 629,7 50, dated July 25, 1899.

Application filed November 28, 1898. Serial NO- 697,604, (No model.)

.T0 .CLZZ whom, it may concern:

Be it known that l, HIRAM STEVENS MAXIM, chevalier of the Legion of Honor, civil and mechanical engineer, a citizen of the United States,residing at 18 Queens Gate Place, London, in the county of Middlesex, England, have invented an Improved Method of and Apparatus for Obtaining a High Vacuum, of which the following is a specication.

This invention is an improvement in apparatus for obtaining a high vacuum, and has special reference to a specially-constructed mercury-elevator for use in conjunction with a mercurial pump of the Geissler or Sprengel type for raising and returning mercury to a reservoir after it has passed through the mer.- curial air-pump ready for reuse in the said pump. The said mercury-elevator comprises long steel tubes or pump-barrels in which operate plungers,but which are unprovided with the ordinary stuffing-boxes for the plungers. The outer end of each of the plungers extends through the upper ends of the barrels and is furnished with a block of metal or is otherwise weighted, so as to be sufficiently heavy to keep in a state of tension the rod by which each plungeris connected to the crank-shaft and so prevent chattering of the parts. As no stuit'Y ing-boxes or greasy packin gs are employed at a point where the mercury can reach them, the mercury remains in a pure condition,with the exception of the slight amount of contamination thereof which takes place by its contact with the air and with the steel pump barrels and the valves.

In order that my said invention may be clearly understood and readily carried into eect, I will proceed to describe the same more fully with reference to the accompanying drawings, in which- Figure l is a front elevation, and Fig. 2 an end elevation, of one form of mercury-elevator. Fig. 3 is a sectional elevation, and Fig. 4 a sectional end view, of another form ofthe mercury-elevator. Fig. 5 is a vertical section, on a larger scale, of one of the pump-` barrels and plungers of the mercury-eleva-V tor. Fig. 6 is a vertical section of an airvalve, with which each of the plungers ispro'- vided, as hereinafter described.

Like letters of reference indicate similar parts throughout the drawings. Y

L L are the pu mp-barr/els, and M M are their pistons or plungers. These plungers extend through the upper ends of the pump-barrels and are unprovided with ordinary stuffingboxes, so as to avoid the contamination of the mercury by its contact with greasy packings.

m m are blocks of metal applied to the upper ends of the plungers for increasing their weight and insuring that the connecting-rods m', by which said plungers are coupled to the crank-disks mshall always be kept in a state of tension during Working. Without Weighting the plungers they would have a tendency to float on the mercury as it entered the bar rels and would give rise to chattering of the parts during the working of the elevator.

N and N2 are valves located at the lower end of the pump-barrels L, one of such valves acting as the inlet-valve, past which the mercury flows by gravity from the mercurial airpurnp (or a tank connected therewith) as the plungers rise, and the other acting as the outlet-valve for the mercury as the plungers descend.

In Figs. 3 to 6 I have shown a modiied construction of the mercury-elevator in which the blocks of metal fm are substituted by weights in the form of caps or sleeves mx, connected by screws msto the upper ends of the plungers, Awhich at their ends are made to tit the barrels,`as is best seen in Fig.l 5'. The lower end of each of these caps or sleeves is furnished with a stuffing-box m4 and a leather packing-ring m5, which it will be observed occupies a position entirely out of reach of the mercury, so that the latter cannot become contaminated by contact therewith. Y Thesaid sleeve is also provided with an absorbent ring m6, which at each downward stroke of the plunger enters an oil-cup ,mT on the pump-barrel, thereby becoming charged. with oil and supplying the same to the outside of the barrel, thus'lubricatingit. The leather packing m5 forms an air-tight joint. When the plunger descends, the air contained in the space between the sleeve mx and the barrel L is compressed, thereby creating a pressure in the said space which serves IOO to prevent the mercury from rising between the plun gers and the barrel to such an extent as to escape over the top edge of the barrel. In order to release the compressed air in the said space as the sleeve and plunger complete theirdownward stroke, I provide a valve m8, Fig. G, which is opened each time the plunger descends by a finger m9 on the oscillating connecting-rod m10. This finger acts on the outer end or head of the stem m of the valve each time the said connecting-rod oscillates during the downward stroke of the plunger, thereby depressing the valve against the resistance of a spring m12 and uncovering outlet-apertures m13 in the valve-casing and allowing the air to escape. The lower end of the plunger is provided with a hardened-steel sleeve m14, which is held in place by a collar and screw m15, such sleeve being of a diameter" to t the lower end of the pump-barrel. The portion of the plungers between the ends thereof is of less diameter than the barrels to reduce friction in the working of the said plungers.

O and P are tanks for containing the mercury. The tank O is arranged at a level above the mercury-reservoir of the mercurial airpump and receives the mercury as itis raised by the elevator, and the tank P is arranged at a lower level than the mercurial air-pu mp, so that the mercury will low therefrom into this tank by gravity. The lower tank P is connected with the inlet-valve N by a pipe N3, and the upper tank O is connected with the outlet-valve N2 by a pipe N4.

What I claim is- 1. A mercury-elevator consisting in the combination of pump-barrels open at their upper ends and unprovided with ordinary stufng-boxes, plun gers working in said barrels, a crank-shaft and connecting-rods between the same and the plungers, inlet and outlet valves at the lower ends of the barrels, mercury-receptacles connected with the said valves by piping, one of said receptacles being located at a low level while the other is located at a high level to supply the mercury to the head of a mercurial air-pump, and weights attached to said plungers, such weights being hollow and fitting the exterior of the upper ends of the barrels to constitute chambers in communication with the interior of the barrels, wherein air is compressed at each downward stroke of the plungers, substantially as and for the purpose set forth.

2. In a mercury-elevator the' combination with the pump-barrels unprovided with ordinary stuiing-boxes, the plungers working in said barrels and the crankshaft for working said plungers; oscillatory rods connecting said plungers with the crank-shaft, hollow weighted heads embracing and sliding on the upper portion of the barrels, stuffing-boxes at the lower ends of said heads for making a tight joint between these ends of the heads and the portion of the barrels on which they slide, air-inlet valves on said heads, fingers on the oscillatory rods that connect the plun gers with the crank-shaft, and prolongations on said valves with which the said lingers engage as the plungers descend, whereby the said valves are opened and permit the compressed air within the heads to'cscape, substantially as described.

3. In a mercury-elevator, the combination with the pu iup-barrels unprovided with ordinary stuliingboxes, the plungers working in such barrels, and the crank-shaft for operata ing the plungcrs g oscillatory rods connecting said plungers with the crank-shaft, of hollow weighted heads sliding on said barrels, stuitingboxes at the lower ends of said heads for making a tight joint, airinlet valves on said heads, fingers 011 the oscillatory connectingrods for operating the air-valves as the plungers complete their downward stroke and thereby liberating the air which has become compressed within the heads, absorbent rings on the said heads, oil-cups on the barrels, into which cups the said absorbent rings dip as the plungers descend, thereby becoming charged with oil to lubricate the portion of the barrels on which the heads slide, substantially as described.

In testimony whereof I have hereunto sct my hand, in presence of two subscribing witnesses, this 25th day of November, 1898.

HIRAM STEVENS MAXIM.

lVitnesses:

DRURY W. COOPER, M. LAwsoN Dran. 

